Damped phonograph apparatus



May 8, 1928.

A. MCL. NICOLSON DAMPED PHONOGRAPH APPARATUS Filed March 11, 1927 INVENTOR ALEXANDER McLEAN NICOLSON BY 8% ,4 (a m ATTORNEY Patented May 8, 1928.

. UNITED STATES PATENT OFFICE.

ALEXANDER MQLEAN mconson, 01; NEW YORK, N. Y., Assrenoza'mo wmnn RADIO, met, on NEW YORK, 11.2., A CORPORATION or DELAWARE.

DAMPED PHONOGRAPH APPARATUS.

Application filed March 11, 1927. Serial No. 174,490.

This invention relates to piezo-electric transmitters and more particularly to phonographic devices which are adapted for reversibly transforming pressure or stress 5 variations into electrical oscillations.

It has been known for many years that on subjecting certain crystals to pressure from opposite sides or ends a difference in electrical potential between different parts or sides of the crystals is produced. Such phenomenon of exhibiting dilterences in potential between different regions of the crystals or of exhibiting positive and negative electrification in certain regions is known as piezo-electricity. Also,*when electrical oscillations are applied to such crystals they develop stresses or motions corresponding to the oscillations impressed thereon. Such crystals or plates or rods out therefrom in a proper way may be used to produce such phenomena. Although such efiects may be obtained from crystals of diiterent substances, they are particularly marked in crystals of the substance known as Rochelle salt or sodium-potassium-tartrate.

When a piezo-electric crystal is used in a phonograph transmitter, the transmitter may be connected either directly or through an amplifier to another piezo-electric crystal which may be used as a receiver to produce sound, as more particularly described in my copending applications entitled Composite piezo-electric acoustic device filed Jan. 11, 1927, and Internally clampedcomposite piezo-electric acoustic device filed Jan. 11, 1927. The action of such crystals may also be utilized in response to electric currents from any suitable source, to make suitable and corresponding impressions on a blank plastic record. It will be evident, therefore, that the same crystal device may act equally well as a recorder or reproducer. For use in a phonograph receiver-or transmitter the device is mounted in any suitable 45 manner on a phonograph tone arm to enable the needle or stylus to cooperate with a record disc. In such a device there are likely to be undesirable vibrations which may result from various causes such as chattering and scratch of the phonograph needle on the record, which interfere with the fidelity of recording or reproducing.

An important object of the present invention 1s to provide new and improved reproducing or recording means for phonograph devices by which the effects of such objectionable vibrations may be reduced.

Another object of this invention is to provlde arrangements by which the needle holder may be vibratably secured to the phonograph device without metallic contact therewith, through the .medium of interposed damping material.

Other objects of the invention are to provlde damping means for piezo-electric apparatus, to damp the action of a phonographic device, and to reduce the scratch and chatter of a needle or stylus used with a'piezoelectric crystal in a phonograph.

The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, will best be understood both as to its fundamental principles and as to its practical embodiments, by reference to the specification and accompanying drawing. in which:

Fig. 1 is a perspective view illustrating one embodiment of my invention as applied to a phonograph device;

Fig. 2 is a perspective view illustrating a second embodiment of the invention;

Fig. '3 is a view similar to Fi 2 but showing the use of different dampmg material; and

Fig. 4 is a perspective view illustrating a third embodiment of the invention.

Vhen the needle or stylus of a phonograph transmitter containing a piezoelectric crystal device is caused to ride in the groove of a phonograph record, the pressure variations affecting the crystal produce electrical oscillations, which, when applied to a receiver crystal, produce therein pressure or stress variations, which in turn produce sound waves. It is found that as the needle or stylus of the phonograph device rides in the groove of a record, there is considerable undesirable vibration, such as scratch and chatter of the needle, and I reduce such efcentral flange 6. Suitable dampingvmaterial 7 may be placed on opposite sides of the flange 6 and-held in position by a device which may include members 8 suitably clamped together as by bolts 8 passing therethrough. The damping material 7 may be of suitable material such as paper in the form of sheets or strips, on the opposite sides of said flange 6.

The crystal 5 may be enclosed by a casing 9 spaced therefrom and may be engaged at the end opposite to that en aging the needle holder 2 by a plate 10, suita ly secured thereto as by cementing, bolting or the like and adapted to be drawn towards the needle hold-' er by suitable means including springs 11 and thumb nuts 11 adjustable to exert the desired pressure on the crystal 5 The phonograph device or transmitter may be supported by attaching one of said plates or members 8 to the end 'of the phonograph tone arm 12. The electrical oscillations generated by the vibrations of the crystal 5 may pass through a wire or conductor 13 connected with a suitable electrode l l such as an equatorial conducting beltcoating around the crystal parallel to the base, and a conductor 15 connectan electrode.

ed with electrode, 16 such as a conducting plate attached to one or. both ends of the crystal, or a suitable internal electrode. In this instance, plates 2 and 10 maybe electrically connected together and serve as such In this embodiment, there is damping of boththe needle holder 2 and the crystal 5, which damping tends to reduce undesirable vibrations such as those caused by the scratch and chatter of the needle.

In the arrangement shown in Figs. 2, 3 and 4, the needle holder is yielclably and resiliently held in neutral position without metallic connection to any part of the supporting structure by damping 'material interposed between cooperating members. In the arrangement shown in Figs. 2 and 3, the needle holder is provided with an extension 20, adapted to be interposed between cooperating securing members 18 and 18 forming a part or extension of the-plate 18, which in turn forms a part of the means for converting vibrations of the needle holder into electrical oscillations.

The needle holder is held yiel'dabl and resiliently in neutral position by the amp ing material interposed between the extension 20, and the securing members 18 and 18 under compression sufficient to hold the needle holder in position without metallic contact between the support and the needle holder. v

In the arrangement shown in Fig. 2, the damping material is shown as paper, or other laminated material, while in Fig. 3, it is shown as a single layer of rubber. In these arrangements, the parts other than those described, may be similar to corresponding parts in Fig. 1.

In the embodiment of the invention shown in Fig. 4, the needle holder 23 may be held in a cylindrical bed of damping material 24', such as paper, and having paper or rubber by a cylindrical casing 25, having secured thereto abase plate 26 of suitable material and on which is secured a piezo-electric. crystal 5 engaged at its upper end by an upper plate 27, the plate 27 being urged toward the plate 26 by any suitable means such as straps, or springs or ties not shown.

While I have shown only a few embodiments of my invention, for the purpose of describing the same and illustrating its principles of operation, it is apparent that various changes and modifications may be. made therein without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated by the prior art,

' claims.

or are specifically set forth in the appended I claim 1. A phonographic device including a needle. holder, a piezo-electric element asso ciated therewith, and vibration-dampingty of plies of vibration-damping material enclosing a portion of said needle holder at opposite sides thereof. 3. A phonographic device including a needle holder, a piezo-electric element associated therewith, a swinging arm for sup- .porting needle holder and element, and vibration-damping material interposed be tween said arm and said needle and holder. 4. Av phonographic device including a piezo-electric element, a needle holder associated therewith and having a portion with which said element cooperates and. a projecting flange, vibration-damping material on opposite sides of said flange, a frame enclosing said damping material and acting therethrough to hold said needle holder, and an arm attached to said frame.

' 5. A. phonographic device including a piezo-electric element, a channel-shaped frame cooperating with one end of the crystal, and having its open side facing away therefrom, vibration-damping material, held surrounding said needle holder, a tubular casing surrounding said material, and a piezo-electr c element lncluding a crystal engaging said casing to receive vibrations 20- therefrom.

8. A phonographic device including a needle holder, vibration-damping means including paper woundaround the holder, a

cylindrical casing around said paper to hold 25 the same, and a piezo-electric element including a crystal engaging said cylindrical casing."

Signed at New York city, in the county of New York and State of New York, this tenth 30 day of'March, A. D. 1927. v

v ALEXANDER McLEAN NICOLSON. 

